To the best of our knowledge, no photometric data are available for the other nights. Therefore, we looked to the [Sii] 6730 Å  emission line which has extremely similar profiles from night-to-night, and very small night-to-night flux variations. The profiles of this line show the typical features of forbidden lines in CTTS, namely a high- and a low-velocity component (HVC and LVC, respectively) wherein the HVC is not expected to show any variability on these short timescales (see § REF ) [1]}, [2]}, [3]}, [4]}. Taking the flux calibrated [Sii] 6730 Å  HVC (the 17 June epoch) as a reference (the [Oi] 6300 Å  line can also be used, but is less straightforward to analyse because it is in a region of telluric contamination), we re-scaled each epoch by the amount that was necessary to match the flux of its HVC with the flux calibrated one.
